Motor control system



Oct.r3, 1944.

J. WHITE MOTOR CONTROL SYSTEM FiledAug. 2l, 1942 fac ATTORNEY/f Patented Oct. 3, 1944 MOTOR CONTROL SYSTEM Joe White, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application August 21, 1942, Serial No. 455,633

8 Claims.

This invention relates to a system for controlling an electric servo motor for operating a device such as the steering apparatus of a vehicle in either direction. It is an object of the present invention to provide a system of control whereby the motor may move an element such as a steering arm, a limited distance on either side of neutral or center position and whereby the arm may be brought back to the neutral or center position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

The three figures of the drawing are wiring diagrams illustrating three statuses of the control system. Positive line wire I and negative line wire I I are connected with a current source such as a storage battery 5. Wire I9`is connected with the system by switches I2, I3 and I4. Switch I2 is the main control switch and is closed to cause the motor M to operate in any manner depending on whether switch I2 alone 'is closed,

or whether switches I3 or I4 are closed concur.

rently with switch I2. The reversing of current through the armature of motor M is controlled by a relay I5 having magnet core I6 surrounded by a coil I1 having one end connected by wire I8 with negative line I I and the other end connected by wire I9 with blade 4I of a limit switch unit 40. The armature 20 of relay I5 is normally urged away from the core I6 by a spring 2l. Armature 2Il insulatingly supports contacts 22 and 24 for making engagement with contacts 23 and 25 and insulatingly supports contacts 26 and 28 for engaging contacts 21 and 29. As shown in Fig. l, contacts 24 and 25`are normally engaged and contacts 28 and 29 are normally engaged. Switch I2 is connected with motor iield winding F which is connected with contacts 22 and 24.

Contact 23 is connected by wire 30 with a wire 3| connecting contact 29 with armature A. Ar-

mature A is connected with wire 32 connecting` Contacts 26 and 28 49. I2. I3 and with blade 5I of centering switch unit 58.

The unit 5I) comprises blade 5I carrying a con- `5o 43 and 45 carried respectively by blades 41 and Blade 41 is connected by wire 46 with switch Blade 49 is connected by wire 48 with switch tact 52 for engaging a contact 53 carried by blade 54 connected by wire 55 with switch I4. Both switchunits 40 and 50 are controlled by a cam operated by shaft 6I driven by motor A thru speed reducing gear unit 62. The shaft operates an arm 10 connectible with a device such as a steering mechanism operated by the servo motor. Cam 60 provides a rise 63, a dwell or land 64 and a rise engageable with a follower 49a on the end of blade 49. Cam 60 provides a rise 66 and a land 61 for engaging a follower 54a provided by the blade 54.

The neutral or center position of the operating arm 10 is shown in Fig. 1. 'When it is desired to move the arm up or counterclockwise as indicated by the arrow 1I in Fig. 1, the switch I2 only is closed. This causes current to now through the field F and the armature A as indicated by the arrows on the field F and arrow af on armature A. The shaft 6I is rotated counterclockwise and will continue to move the arm 'I0 in that direction until the switch I2 is opened or until the cam rise 65 engages the follower 49a and causes it to rise to position 49am` thereby closing contacts 42 and 43 thereby connecting the relay magnet I1 across the lines I and II thereby attracting the armature 20 toward the core I6 to effect a reversal of flow of current across the armature A as indicated by arrow ar and thereby causing the cam 60 to rotate clockwise until the contact 42 is separated from the contact 43 whereupon the relay coil I1 will be deenergized and the control system will return to the condition shown in Fig. 1 and then counterclockwise rotation of cam 60 will be repeated until contacts 42 and 43 are closed and then reverse rotation will take place again and this cycle will be repeated so long as the switch I2 remains closed. Consequently the closing of the switch causes the arm 1I) to move into a certain position 10| a certain distance away from center position and in position 1IiI to oscillate slightly.

When it is desired to cause the arm 13 to move down or clockwise indicated by arrow 12 in Fig. 2, both switches I2 and I3 are closed,

thereby causing the relay magnet coil I1 to be energized and to attract armature 20 toward the left to separate contacts 24, 25 and 28, 29 and -to engage contacts 22,23 and 25, 21 thereby Clockwise rotation of the arm 1U will continue so long as the switch I3 is closed, but no longer than required for the cam 60 to move so that its lobe E3 arrives at position 63X which allows the blade 49 to move to position 49x which causes contact 45 to be separated from contact 44 thereby disconnecting the relay magnet coil I'I from the current source and thereby resulting in return of the armature 20 to the position shown in Fig. l, which causes the armature current to flow in the direction of arrow af and then the cam 3B begins moving counterclockwise to cause the cam rise 63X to push follower 49a up thereby causing contact 45 to reengage contact 44 whereupon relay coil 7U becomes energized again lto attract armature Z and cause the moto-r to rotate the arm clockwise until cam rise 63 becomes again into the position 63X which results in reversal of the motor so that the cam 60 starts moving counterclo-ckwise again and this cycle `is repeated so long as both switches I2 and I3 vare closed. Therefore the closing of switch I3 as well as switch I2 will cause the motor to rotate the arm clockwise until the arm is moved into a certain position 'lor a certain distance away in a clockwise direction from center position and at that new position the arm 'I0 will oscillate through a small angle. If switch I3 is opened before the arm 'Ill has moved into position Tr, the motor will rotate the arm 10 in a counterclockwise direction until the switch I2 is opened or until the arm 'I0 has moved into the position TUI.

When it is desired to bring the arm IIJ back to the center position '10c from the positions 'IDI or lib', or any intermediate position, switches I2 and I4 are closed while Vswitch I3 is opened as shown in Fig. 3. When the follower` 49a of blade 49 is substantially one-half way between cam rises 83 and 65, the follower 54a. of blade 54 is being engaged by cam rise 66, thereby causing blade 54 to move between the positions 54x and 54g (Fig. 3) alternately separating and reengaging contacts 52 and 53. If the contacts 52, 53 are engaged when switch I4 is closed, then the relay I5 is in the status shown in Fig. 2 and the cam 60 rotates clockwise as lindicated by arrow 'I2 to cause separation 4of contact 53 from contact 52, whereupon the status of the relay returns to that shown in Fig. 1, and the motor rotates the arm 'Ill in the direction of the arrow 7 1, thereby causing the contacts 53 and 52 to reengage and the status of the relay returns to that shown in Fig. 2, whereupon the motor rotates the arm lll in the direction ofthe arrow 'l2 again. This cycle will be repeated solong as switches I2 and I4 remain closed.

The control system is under the control of the manually operated switches I2, I3 and I4. The closing of switch I2 produces counterclockwise rotation. of arm 'lil to position 10| unless the switch I 2 is opened soon. The closing of switches I?. and I3 produces clockwise rotation of arm 'Ill to position lr unless switch I3 is opened sooner. The closing of switches I2 and I4 results in return of arm I0 to position 16e.

While the embodiment of the present invention as herein disclosed, constitutes a. preferred form, it is to be understood that other forms might be adopted, all coming Within the scope of the claims which follow.

What is claimed is as follows:

1. A motor control system comprising current source, an electric motor having a leld and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current flow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current ow through the armature, a relay magnet coil connected with a current source wire and operating when energized to cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite direction, a circuit for connecting the relay coil f with the first mentioned current source wire and comprising the manually closed switch and a normally-open limit switch, and a cam operated by the shaft for closing the limit switch when the arm has been moved into a certain position thereby causing the relay coil to reverse armature current flow and arm to move in the opposite direction until the limit switch opens, the rst movement of the arm then being resumed until the limit switch closes, thereby resulting in a r slight oscillation rof the arm at said certain position.

2. A motor control system comprising current source, an electric motor having a field and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current flow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current iiow through the armature, a relay magnet coil connected with a current source wire and operating when energized to cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite direction, a circuit for connecting the relay coil with the iirst mentioned current source wire and comprising in series a second manually closed switch and a normally closed limit switch, the closing of both manually operated switches causing the arm to move in a direction opposite to the rst direction, and a cam operated by the shaft and movable to such position that, when the arm hasV moved to a certain positionin its opposite direction of movement, the limit switch opens thereby restoring the relay contacts to original status and causing the arm to move in the rst mentioned direction and said cam to close the limit switch whereupon the arm again moves in said opposite direction until the limit switch opens, thereby resulting in a slight oscillation of the arm at said certain position in the opposite direction of its movement.

3. A motor control system comprising current source, an electric motor having a iield and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current ow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current flow through the armature, a relay magnet coil connected with a current source wire and operating when energized t0 Cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite direction, a circuit for connecting the relay coil with the first mentioned current source Wire and comprising the manually closed switch and a normally open limit switch, and a cam operated by the shaft for closing the limit switch when the arm has been moved into a certain position thereby causing the relay coil to reverse armature current flow and arm to move in the opposite direction until the limit switch opens, the first movement of the arm then being resumed until the limit switch closes, thereby resulting in a slight oscillation of the arm at said certain position, and another circuit for connecting the relay coil with the current source and including a second manually operated switch and a centering switch having its contacts closed when the arm is moving from a center position in said first mentioned direction of movement, the closing of the second manually operated switch while the first manually operated switch is closed causing energization of the relay coil and reversal of arm movement until it reaches center position, and a cam operated by the shaft for opening the centering switch when the arm arrives at center position thereby causing the arm to rotate again in the first mentioned direction and the centering switch to close, thereby resulting in a slight oscillation of the arm at its center position.

4. A motor control system comprising current source, an electric motor having a field and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current flow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current flow through the armature, a relay magnet coil connected with a current source wire and operating when energized to cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite direction. a circuit for connecting the relay coil with the first mentioned current source wire and comprising in series a second manually closed switch and a normally closed limit switch, the closing of both manually operated switches causing the arm to move in a direction opposite to the first direction, and a cam operated by the shaft and movable to such position that. when the arm has moved to a certain position in its opposite direction of movement, the limit switch opens thereby restoring'the relay contacts to original status and causing the arm to move in the first mentioned direction and said cam to close the limit switch whereupon the arm again moves in said opposite direction until the limit switch opens, thereby resulting in a slight oscillation of the arm at said certain position in the opposite direction of its movement, and another circuit for connecting the relay coil with the current source and including a third manually operated switch and a centering switch having its contacts open when the arm is moving from a center position in the second mentioned direction of movement, the third and first switches being closed while the second switch is open, whereby reversal of movement of the arm from second to first directions takes place, and a cam operated by the shaft and so related to the arm that, upon return of the arm to center position during movement of the arm in the first direction, the centering switch closes and the relay coil operates to effect movement of the arm in the second direction until the centering switch opens, thereby causing slight oscillation of the arm at its center position.

5. A motor control system comprising current source, an electric motor having a field and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current fiow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current fiow through the armature, a relay magnet coil connected with a current source wire and operating when energized to cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite direction` a circuit for connecting the relay coil with the first mentioned current source wire and comprising the manually closed switch and a normally open limit switch, and a cam operated by the shaft for closing the limit switch when the arm has been moved into a certain position thereby causing the relay coil to reverse armature current flow and arm to move in the opposite direction until the limit switch opens, the first movement of the arm then being resumed until the limit switch closes, thereby resulting in a slight oscillation of the arm at said certain position, another circuit fcr connecting the relay coil with the first mentioned current source wire and comprising in series a second manually closedA switch and a second normally closed limit switch, the closing of both manually operated switches causing the arm to move in a direction opposite to the first direction, and a second cam operated by the shaft and movable to such position, that when the arm has moved to a certain position in its opposite direction of movement, the second limit switch opens thereby restoring the relay contacts to original status and causing the arm to move in the first mentioned direction and said second cam to close the second limit switch whereupon the arm again moves in said opposite direction until the second limit switch opens, thereby resulting in a slight oscillation of the arm at said certain position in the opposite direction of its movement.

6. A motor control system comprising current source, an electric motor having a field and an armature, a shaft driven thereby, an arm operated by the shaft, a circuit for so connecting the source and motor that the arm moves in a certain direction, said circuit comprising a manually closed switch and normally closed pairs of relay switch contacts for causing current iiow through the armature in a certain direction, other pairs of normally open relay switch contacts for effecting reversal of current fiow through the armature, a relay magnet coil connected with a current source wire and operating when energized to cause the separation of the normally closed relay contacts and the engagement of the normally open relay contacts thereby to effect rotation of the arm in the opposite directions, a circuit for connecting the relay coil with the first mentioned current source wire and comprising the manually closed switch and a normally open limit switch, and a cam voperated by the shaft for closing the limit switch when the arm has been moved into a certain position thereby causing the relay coil to reverse armature current flow and arm to move in the opposite direction until the limit switch opens, the rst movement of the arm then being resumed the limit switch closes, thereby resulting in a slight oscillation of the arm at said certain position, another circuit for connecting the relay coil with the rst mentioned current source `wire and comprising in series a second manually closed switch and a second normally closed limit switch, the closing of both manually operated switches causing the arm lto move in a direction opposite to the rst direction, and a second cam operated by the shaft and movable to such position, that when the arm has moved to a certain position in its opposite direction of movement, the second limit switch opens thereby restoring the relay contacts to original status and causing the arm tomove in the rst mentioned direction and said second cam to close the second limit switch whereupon the arm again moves in said opposite direction until the second limit switch opens, thereby resulting in a slight oscillation of the arm at said certain `position in the opposite direction of its movement, and a third circuit for connecting the relay coil with the lcurrent source and including a third manually operated switchv and a centering switch having its contacts closed when the arm is moving from a center position in the rst mentioned direction of movement as the result of closing only the rst manually operated switch, or having its contacts open when the arm is moving from a center position in the second mentioned direction of movement as result of closing the first and second manually operated switches, a centering switch operating cam driven by the shaft in predetermined relation to the arm whereby the closing of the rst and third switches, while the second switch is opened, causes reversal of arm movement (from movement in the rst direction of movement away from center position) until center position is reached or reversal of arm movement (from movement in the second mentioned direction may center position) until center position is reached, whereby the arm can be returned to center position from a position on either side of center.

7. A motor control system comprising a current source and an electric motor having an armature and eld, an arm operated by the motor, a manually closed switch and a circuit controlled thereby for eiecting connection with the motor and source for operation of the arm in one direction from a center position, a second manually closed switch and a circuit operated thereby and effective while the rst switch is closed to cause a reversal of current flow through the motor armature to cause the arm to move in a direction opposite to the first direction, and a third manually closed switch and a circuit controlled thereby and effective while the rst switch is closed and the second switch is open to cause the arm to return to center position.

8, A control device for a reversible electric motor having eld and armature circuits adapted to be connected to a source of electric power, comprising, an arm operated by said motor.; an electromagnetic relay adapted, in its normal position to complete motor connections to effect motor operation to rotate the arm in one direction and in its attracted position to complete motor connections to eiTect rotation of the motor for turning the arm in the opposite direction; a manually operable switch for connecting the motor with the power source across the relay for eiecting `rotation of the arm in said one direction and maintaining the relay in its normal position; a second manually operable switch adapted, when closed while the first switch is closed, to render the relay active to change motor connections for moving the arm in a reverse direction; a third manually operable switch for completing connections to the motor to render it elTective to return the arm to normal position while the first switch is closed and the second switch open; and limiting switches controlled by said arm for limiting its rotative movement in either direction.

JOE WHITE. 

